An Ofsted inspection report into King’s Science Academy in Bradford found that it had to improve “leadership and management at all levels”.

Last year it was visited by the Prime Minister, who later personally praised it in a letter to the school’s principal Sajid Raza.

The report is the eighth into the new wave of free schools which have been set up by Education secretary Michael Gove in September 2011. Of those eight, four of the Ofsted reports have been critical of the free schools.

Ofsted staff found during an investigation last month that students were made to recite the school’s motto before every class but exclusions levels were running high.

In the inspection carried out in the middle of last month, students complained to the inspectors that they were being made to spend too long at school.

Students are required to be at school from 8am til 4.30pm every day, including a half an hour period for reading.

The Ofsted report said: “Some students told inspectors that they think that the academy day is too long, especially when they choose to, or have to stay for an extra hour to do their homework.”

It added that students – four out of 10 of whom were eligible for free school meals – enjoyed most lessons when they were “able to investigate things for themselves; not always being told what to do in lessons and to carry out instructions”.

The inspectors found evidence of good and inadequate teaching at the free school. They said: “When tasks fail to enthuse and excite students, they become bored and passive in lessons.”

There was not enough space in the school, which had only moved to its current location last October for practical experiments in science or design and technology.

Creative subjects like art, design, music and performing arts were not taught regularly, Ofsted found.

Mr Raza told The Daily Telegraph on Thursday night: “It is kind of a long day compared to most school but the vast majority of our parent s and our stidents are fine with it.

“We do have some students who find the day a bit long but you don’t have a perfect scenario. We are work in the heart of a socially deprived neighbourhood where a lot of our kinds would invariably be on the streets.”

He pointed to other more glowing reports and suggested that the Ofsted inspectors had difficulties in understanding the way the school operated. He said: “There was a lot of things that we do that they could not understand our model of education.”

Natalie Evans, Director of the New Schools Network said: "Free Schools are quite rightly subject to the same inspection regime as another school in England. It is very early days and whilst we are seeing some good results coming through - Etz Chaim and E-ACT's Aldborough Free School for example - others have areas they need to improve upon.

"Formal inspection of Free Schools is a key part of the accountability regime. Ultimately though, Free Schools are accountable to the parents who have entrusted them with their child's education and their success sits squarely with those parents continuing to have confidence in each school's ability to provide a great education from Day 1 onwards."